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 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #ifndef pldhash_h___

 #define pldhash_h___

 /*

  * Double hashing, a la Knuth 6.

  */

 #include "mozilla/fallible.h"

 #include "mozilla/MemoryReporting.h"

 #include "mozilla/Types.h"

 #include "nscore.h"

 #if defined(__GNUC__) && defined(__i386__)

 #define PL_DHASH_FASTCALL __attribute__ ((regparm (3),stdcall))

 #elif defined(XP_WIN)

 #define PL_DHASH_FASTCALL __fastcall

 #else

 #define PL_DHASH_FASTCALL

 #endif

 /*

  * Table size limit; do not exceed.  The max capacity used to be 1<<23 but that

  * occasionally that wasn't enough.  Making it much bigger than 1<<26 probably

  * isn't worthwhile -- tables that big are kind of ridiculous.  Also, the

  * growth operation will (deliberately) fail if |capacity * entrySize|

  * overflows a uint32_t, and entrySize is always at least 8 bytes.

  */

 #undef PL_DHASH_MAX_SIZE

 #define PL_DHASH_MAX_SIZE     ((uint32_t)1 << 26)

 /* Minimum table size, or gross entry count (net is at most .75 loaded). */

 #ifndef PL_DHASH_MIN_SIZE

 #define PL_DHASH_MIN_SIZE 16

 #elif (PL_DHASH_MIN_SIZE & (PL_DHASH_MIN_SIZE - 1)) != 0

 #error "PL_DHASH_MIN_SIZE must be a power of two!"

 #endif

 /*

  * Multiplicative hash uses an unsigned 32 bit integer and the golden ratio,

  * expressed as a fixed-point 32-bit fraction.

  */

 #define PL_DHASH_BITS           32

 #define PL_DHASH_GOLDEN_RATIO   0x9E3779B9U

 /* Primitive and forward-struct typedefs. */

 typedef uint32_t                PLDHashNumber;

 typedef struct PLDHashEntryHdr  PLDHashEntryHdr;

 typedef struct PLDHashEntryStub PLDHashEntryStub;

 typedef struct PLDHashTable     PLDHashTable;

 typedef struct PLDHashTableOps  PLDHashTableOps;

 /*

  * Table entry header structure.

  *

  * In order to allow in-line allocation of key and value, we do not declare

  * either here.  Instead, the API uses const void *key as a formal parameter.

  * The key need not be stored in the entry; it may be part of the value, but

  * need not be stored at all.

  *

  * Callback types are defined below and grouped into the PLDHashTableOps

  * structure, for single static initialization per hash table sub-type.

  *

  * Each hash table sub-type should nest the PLDHashEntryHdr structure at the

  * front of its particular entry type.  The keyHash member contains the result

  * of multiplying the hash code returned from the hashKey callback (see below)

  * by PL_DHASH_GOLDEN_RATIO, then constraining the result to avoid the magic 0

  * and 1 values.  The stored keyHash value is table size invariant, and it is

  * maintained automatically by PL_DHashTableOperate -- users should never set

  * it, and its only uses should be via the entry macros below.

  *

  * The PL_DHASH_ENTRY_IS_LIVE function tests whether entry is neither free nor

  * removed.  An entry may be either busy or free; if busy, it may be live or

  * removed.  Consumers of this API should not access members of entries that

  * are not live.

  *

  * However, use PL_DHASH_ENTRY_IS_BUSY for faster liveness testing of entries

  * returned by PL_DHashTableOperate, as PL_DHashTableOperate never returns a

  * non-live, busy (i.e., removed) entry pointer to its caller.  See below for

  * more details on PL_DHashTableOperate's calling rules.

  */

 struct PLDHashEntryHdr {

     PLDHashNumber       keyHash;        /* every entry must begin like this */

 };

 MOZ_ALWAYS_INLINE bool

 PL_DHASH_ENTRY_IS_FREE(PLDHashEntryHdr* entry)

 {

     return entry->keyHash == 0;

 }

 MOZ_ALWAYS_INLINE bool

 PL_DHASH_ENTRY_IS_BUSY(PLDHashEntryHdr* entry)

 {

     return !PL_DHASH_ENTRY_IS_FREE(entry);

 }

 MOZ_ALWAYS_INLINE bool

 PL_DHASH_ENTRY_IS_LIVE(PLDHashEntryHdr* entry)

 {

     return entry->keyHash >= 2;

 }

 /*

  * A PLDHashTable is currently 8 words (without the PL_DHASHMETER overhead)

  * on most architectures, and may be allocated on the stack or within another

  * structure or class (see below for the Init and Finish functions to use).

  *

  * To decide whether to use double hashing vs. chaining, we need to develop a

  * trade-off relation, as follows:

  *

  * Let alpha be the load factor, esize the entry size in words, count the

  * entry count, and pow2 the power-of-two table size in entries.

  *

  *   (PLDHashTable overhead)    > (PLHashTable overhead)

  *   (unused table entry space) > (malloc and .next overhead per entry) +

  *                                (buckets overhead)

  *   (1 - alpha) * esize * pow2 > 2 * count + pow2

  *

  * Notice that alpha is by definition (count / pow2):

  *

  *   (1 - alpha) * esize * pow2 > 2 * alpha * pow2 + pow2

  *   (1 - alpha) * esize        > 2 * alpha + 1

  *

  *   esize > (1 + 2 * alpha) / (1 - alpha)

  *

  * This assumes both tables must keep keyHash, key, and value for each entry,

  * where key and value point to separately allocated strings or structures.

  * If key and value can be combined into one pointer, then the trade-off is:

  *

  *   esize > (1 + 3 * alpha) / (1 - alpha)

  *

  * If the entry value can be a subtype of PLDHashEntryHdr, rather than a type

  * that must be allocated separately and referenced by an entry.value pointer

  * member, and provided key's allocation can be fused with its entry's, then

  * k (the words wasted per entry with chaining) is 4.

  *

  * To see these curves, feed gnuplot input like so:

  *

  *   gnuplot> f(x,k) = (1 + k * x) / (1 - x)

  *   gnuplot> plot [0:.75] f(x,2), f(x,3), f(x,4)

  *

  * For k of 2 and a well-loaded table (alpha > .5), esize must be more than 4

  * words for chaining to be more space-efficient than double hashing.

  *

  * Solving for alpha helps us decide when to shrink an underloaded table:

  *

  *   esize                     > (1 + k * alpha) / (1 - alpha)

  *   esize - alpha * esize     > 1 + k * alpha

  *   esize - 1                 > (k + esize) * alpha

  *   (esize - 1) / (k + esize) > alpha

  *

  *   alpha < (esize - 1) / (esize + k)

  *

  * Therefore double hashing should keep alpha >= (esize - 1) / (esize + k),

  * assuming esize is not too large (in which case, chaining should probably be

  * used for any alpha).  For esize=2 and k=3, we want alpha >= .2; for esize=3

  * and k=2, we want alpha >= .4.  For k=4, esize could be 6, and alpha >= .5

  * would still obtain.

  *

  * The current implementation uses a configurable lower bound on alpha, which

  * defaults to .25, when deciding to shrink the table (while still respecting

  * PL_DHASH_MIN_SIZE).

  *

  * Note a qualitative difference between chaining and double hashing: under

  * chaining, entry addresses are stable across table shrinks and grows.  With

  * double hashing, you can't safely hold an entry pointer and use it after an

  * ADD or REMOVE operation, unless you sample table->generation before adding

  * or removing, and compare the sample after, dereferencing the entry pointer

  * only if table->generation has not changed.

  *

  * The moral of this story: there is no one-size-fits-all hash table scheme,

  * but for small table entry size, and assuming entry address stability is not

  * required, double hashing wins.

  */

 struct PLDHashTable {

     const PLDHashTableOps *ops;         /* virtual operations, see below */

     void                *data;          /* ops- and instance-specific data */

     int16_t             hashShift;      /* multiplicative hash shift */

     /*

      * |recursionLevel| is only used in debug builds, but is present in opt

      * builds to avoid binary compatibility problems when mixing DEBUG and

      * non-DEBUG components.  (Actually, even if it were removed,

      * sizeof(PLDHashTable) wouldn't change, due to struct padding.)

      */

     uint16_t            recursionLevel; /* used to detect unsafe re-entry */

     uint32_t            entrySize;      /* number of bytes in an entry */

     uint32_t            entryCount;     /* number of entries in table */

     uint32_t            removedCount;   /* removed entry sentinels in table */

     uint32_t            generation;     /* entry storage generation number */

     char                *entryStore;    /* entry storage */

 #ifdef PL_DHASHMETER

     struct PLDHashStats {

         uint32_t        searches;       /* total number of table searches */

         uint32_t        steps;          /* hash chain links traversed */

         uint32_t        hits;           /* searches that found key */

         uint32_t        misses;         /* searches that didn't find key */

         uint32_t        lookups;        /* number of PL_DHASH_LOOKUPs */

         uint32_t        addMisses;      /* adds that miss, and do work */

         uint32_t        addOverRemoved; /* adds that recycled a removed entry */

         uint32_t        addHits;        /* adds that hit an existing entry */

         uint32_t        addFailures;    /* out-of-memory during add growth */

         uint32_t        removeHits;     /* removes that hit, and do work */

         uint32_t        removeMisses;   /* useless removes that miss */

         uint32_t        removeFrees;    /* removes that freed entry directly */

         uint32_t        removeEnums;    /* removes done by Enumerate */

         uint32_t        grows;          /* table expansions */

         uint32_t        shrinks;        /* table contractions */

         uint32_t        compresses;     /* table compressions */

         uint32_t        enumShrinks;    /* contractions after Enumerate */

     } stats;

 #endif

 };

 /*

  * Size in entries (gross, not net of free and removed sentinels) for table.

  * We store hashShift rather than sizeLog2 to optimize the collision-free case

  * in SearchTable.

  */

 #define PL_DHASH_TABLE_SIZE(table) \

     ((uint32_t)1 << (PL_DHASH_BITS - (table)->hashShift))

 /*

  * Table space at entryStore is allocated and freed using these callbacks.

  * The allocator should return null on error only (not if called with nbytes

  * equal to 0; but note that pldhash.c code will never call with 0 nbytes).

  */

 typedef void *

 (* PLDHashAllocTable)(PLDHashTable *table, uint32_t nbytes);

 typedef void

 (* PLDHashFreeTable) (PLDHashTable *table, void *ptr);

 /*

  * Compute the hash code for a given key to be looked up, added, or removed

  * from table.  A hash code may have any PLDHashNumber value.

  */

 typedef PLDHashNumber

 (* PLDHashHashKey)   (PLDHashTable *table, const void *key);

 /*

  * Compare the key identifying entry in table with the provided key parameter.

  * Return true if keys match, false otherwise.

  */

 typedef bool

 (* PLDHashMatchEntry)(PLDHashTable *table, const PLDHashEntryHdr *entry,

                       const void *key);

 /*

  * Copy the data starting at from to the new entry storage at to.  Do not add

  * reference counts for any strong references in the entry, however, as this

  * is a "move" operation: the old entry storage at from will be freed without

  * any reference-decrementing callback shortly.

  */

 typedef void

 (* PLDHashMoveEntry)(PLDHashTable *table, const PLDHashEntryHdr *from,

                      PLDHashEntryHdr *to);

 /*

  * Clear the entry and drop any strong references it holds.  This callback is

  * invoked during a PL_DHASH_REMOVE operation (see below for operation codes),

  * but only if the given key is found in the table.

  */

 typedef void

 (* PLDHashClearEntry)(PLDHashTable *table, PLDHashEntryHdr *entry);

 /*

  * Called when a table (whether allocated dynamically by itself, or nested in

  * a larger structure, or allocated on the stack) is finished.  This callback

  * allows table->ops-specific code to finalize table->data.

  */

 typedef void

 (* PLDHashFinalize)  (PLDHashTable *table);

 /*

  * Initialize a new entry, apart from keyHash.  This function is called when

  * PL_DHashTableOperate's PL_DHASH_ADD case finds no existing entry for the

  * given key, and must add a new one.  At that point, entry->keyHash is not

  * set yet, to avoid claiming the last free entry in a severely overloaded

  * table.

  */

 typedef bool

 (* PLDHashInitEntry)(PLDHashTable *table, PLDHashEntryHdr *entry,

                      const void *key);

 /*

  * Finally, the "vtable" structure for PLDHashTable.  The first eight hooks

  * must be provided by implementations; they're called unconditionally by the

  * generic pldhash.c code.  Hooks after these may be null.

  *

  * Summary of allocation-related hook usage with C++ placement new emphasis:

  *  allocTable          Allocate raw bytes with malloc, no ctors run.

  *  freeTable           Free raw bytes with free, no dtors run.

  *  initEntry           Call placement new using default key-based ctor.

  *                      Return true on success, false on error.

  *  moveEntry           Call placement new using copy ctor, run dtor on old

  *                      entry storage.

  *  clearEntry          Run dtor on entry.

  *  finalize            Stub unless table->data was initialized and needs to

  *                      be finalized.

  *

  * Note the reason why initEntry is optional: the default hooks (stubs) clear

  * entry storage:  On successful PL_DHashTableOperate(tbl, key, PL_DHASH_ADD),

  * the returned entry pointer addresses an entry struct whose keyHash member

  * has been set non-zero, but all other entry members are still clear (null).

  * PL_DHASH_ADD callers can test such members to see whether the entry was

  * newly created by the PL_DHASH_ADD call that just succeeded.  If placement

  * new or similar initialization is required, define an initEntry hook.  Of

  * course, the clearEntry hook must zero or null appropriately.

  *

  * XXX assumes 0 is null for pointer types.

  */

 struct PLDHashTableOps {

     /* Mandatory hooks.  All implementations must provide these. */

     PLDHashAllocTable   allocTable;

     PLDHashFreeTable    freeTable;

     PLDHashHashKey      hashKey;

     PLDHashMatchEntry   matchEntry;

     PLDHashMoveEntry    moveEntry;

     PLDHashClearEntry   clearEntry;

     PLDHashFinalize     finalize;

     /* Optional hooks start here.  If null, these are not called. */

     PLDHashInitEntry    initEntry;

 };

 /*

  * Default implementations for the above ops.

  */

 NS_COM_GLUE void *

 PL_DHashAllocTable(PLDHashTable *table, uint32_t nbytes);

 NS_COM_GLUE void

 PL_DHashFreeTable(PLDHashTable *table, void *ptr);

 NS_COM_GLUE PLDHashNumber

 PL_DHashStringKey(PLDHashTable *table, const void *key);

 /* A minimal entry contains a keyHash header and a void key pointer. */

 struct PLDHashEntryStub {

     PLDHashEntryHdr hdr;

     const void      *key;

 };

 NS_COM_GLUE PLDHashNumber

 PL_DHashVoidPtrKeyStub(PLDHashTable *table, const void *key);

 NS_COM_GLUE bool

 PL_DHashMatchEntryStub(PLDHashTable *table,

                        const PLDHashEntryHdr *entry,

                        const void *key);

 NS_COM_GLUE bool

 PL_DHashMatchStringKey(PLDHashTable *table,

                        const PLDHashEntryHdr *entry,

                        const void *key);

 NS_COM_GLUE void

 PL_DHashMoveEntryStub(PLDHashTable *table,

                       const PLDHashEntryHdr *from,

                       PLDHashEntryHdr *to);

 NS_COM_GLUE void

 PL_DHashClearEntryStub(PLDHashTable *table, PLDHashEntryHdr *entry);

 NS_COM_GLUE void

 PL_DHashFreeStringKey(PLDHashTable *table, PLDHashEntryHdr *entry);

 NS_COM_GLUE void

 PL_DHashFinalizeStub(PLDHashTable *table);

 /*

  * If you use PLDHashEntryStub or a subclass of it as your entry struct, and

  * if your entries move via memcpy and clear via memset(0), you can use these

  * stub operations.

  */

 NS_COM_GLUE const PLDHashTableOps *

 PL_DHashGetStubOps(void);

 /*

  * Dynamically allocate a new PLDHashTable using malloc, initialize it using

  * PL_DHashTableInit, and return its address.  Return null on malloc failure.

  * Note that the entry storage at table->entryStore will be allocated using

  * the ops->allocTable callback.

  */

 NS_COM_GLUE PLDHashTable *

 PL_NewDHashTable(const PLDHashTableOps *ops, void *data, uint32_t entrySize,

                  uint32_t capacity);

 /*

  * Finalize table's data, free its entry storage (via table->ops->freeTable),

  * and return the memory starting at table to the malloc heap.

  */

 NS_COM_GLUE void

 PL_DHashTableDestroy(PLDHashTable *table);

 /*

  * Initialize table with ops, data, entrySize, and capacity.  Capacity is a

  * guess for the smallest table size at which the table will usually be less

  * than 75% loaded (the table will grow or shrink as needed; capacity serves

  * only to avoid inevitable early growth from PL_DHASH_MIN_SIZE).  This will

  * crash if it can't allocate enough memory, or if entrySize or capacity are

  * too large.

  */

 NS_COM_GLUE void

 PL_DHashTableInit(PLDHashTable *table, const PLDHashTableOps *ops, void *data,

                   uint32_t entrySize, uint32_t capacity);

 /*

  * Initialize table. This is the same as PL_DHashTableInit, except that it

  * returns a boolean indicating success, rather than crashing on failure.

  */

 NS_COM_GLUE bool

 PL_DHashTableInit(PLDHashTable *table, const PLDHashTableOps *ops, void *data,

                   uint32_t entrySize, uint32_t capacity,

                   const mozilla::fallible_t& ) MOZ_WARN_UNUSED_RESULT;

 /*

  * Finalize table's data, free its entry storage using table->ops->freeTable,

  * and leave its members unchanged from their last live values (which leaves

  * pointers dangling).  If you want to burn cycles clearing table, it's up to

  * your code to call memset.

  */

 NS_COM_GLUE void

 PL_DHashTableFinish(PLDHashTable *table);

 /*

  * To consolidate keyHash computation and table grow/shrink code, we use a

  * single entry point for lookup, add, and remove operations.  The operation

  * codes are declared here, along with codes returned by PLDHashEnumerator

  * functions, which control PL_DHashTableEnumerate's behavior.

  */

 typedef enum PLDHashOperator {

     PL_DHASH_LOOKUP = 0,        /* lookup entry */

     PL_DHASH_ADD = 1,           /* add entry */

     PL_DHASH_REMOVE = 2,        /* remove entry, or enumerator says remove */

     PL_DHASH_NEXT = 0,          /* enumerator says continue */

     PL_DHASH_STOP = 1           /* enumerator says stop */

 } PLDHashOperator;

 /*

  * To lookup a key in table, call:

  *

  *  entry = PL_DHashTableOperate(table, key, PL_DHASH_LOOKUP);

  *

  * If PL_DHASH_ENTRY_IS_BUSY(entry) is true, key was found and it identifies

  * entry.  If PL_DHASH_ENTRY_IS_FREE(entry) is true, key was not found.

  *

  * To add an entry identified by key to table, call:

  *

  *  entry = PL_DHashTableOperate(table, key, PL_DHASH_ADD);

  *

  * If entry is null upon return, then either the table is severely overloaded,

  * and memory can't be allocated for entry storage via table->ops->allocTable;

  * Or if table->ops->initEntry is non-null, the table->ops->initEntry op may

  * have returned false.

  *

  * Otherwise, entry->keyHash has been set so that PL_DHASH_ENTRY_IS_BUSY(entry)

  * is true, and it is up to the caller to initialize the key and value parts

  * of the entry sub-type, if they have not been set already (i.e. if entry was

  * not already in the table, and if the optional initEntry hook was not used).

  *

  * To remove an entry identified by key from table, call:

  *

  *  (void) PL_DHashTableOperate(table, key, PL_DHASH_REMOVE);

  *

  * If key's entry is found, it is cleared (via table->ops->clearEntry) and

  * the entry is marked so that PL_DHASH_ENTRY_IS_FREE(entry).  This operation

  * returns null unconditionally; you should ignore its return value.

  */

 NS_COM_GLUE PLDHashEntryHdr * PL_DHASH_FASTCALL

 PL_DHashTableOperate(PLDHashTable *table, const void *key, PLDHashOperator op);

 /*

  * Remove an entry already accessed via LOOKUP or ADD.

  *

  * NB: this is a "raw" or low-level routine, intended to be used only where

  * the inefficiency of a full PL_DHashTableOperate (which rehashes in order

  * to find the entry given its key) is not tolerable.  This function does not

  * shrink the table if it is underloaded.  It does not update stats #ifdef

  * PL_DHASHMETER, either.

  */

 NS_COM_GLUE void

 PL_DHashTableRawRemove(PLDHashTable *table, PLDHashEntryHdr *entry);

 /*

  * Enumerate entries in table using etor:

  *

  *   count = PL_DHashTableEnumerate(table, etor, arg);

  *

  * PL_DHashTableEnumerate calls etor like so:

  *

  *   op = etor(table, entry, number, arg);

  *

  * where number is a zero-based ordinal assigned to live entries according to

  * their order in table->entryStore.

  *

  * The return value, op, is treated as a set of flags.  If op is PL_DHASH_NEXT,

  * then continue enumerating.  If op contains PL_DHASH_REMOVE, then clear (via

  * table->ops->clearEntry) and free entry.  Then we check whether op contains

  * PL_DHASH_STOP; if so, stop enumerating and return the number of live entries

  * that were enumerated so far.  Return the total number of live entries when

  * enumeration completes normally.

  *

  * If etor calls PL_DHashTableOperate on table with op != PL_DHASH_LOOKUP, it

  * must return PL_DHASH_STOP; otherwise undefined behavior results.

  *

  * If any enumerator returns PL_DHASH_REMOVE, table->entryStore may be shrunk

  * or compressed after enumeration, but before PL_DHashTableEnumerate returns.

  * Such an enumerator therefore can't safely set aside entry pointers, but an

  * enumerator that never returns PL_DHASH_REMOVE can set pointers to entries

  * aside, e.g., to avoid copying live entries into an array of the entry type.

  * Copying entry pointers is cheaper, and safe so long as the caller of such a

  * "stable" Enumerate doesn't use the set-aside pointers after any call either

  * to PL_DHashTableOperate, or to an "unstable" form of Enumerate, which might

  * grow or shrink entryStore.

  *

  * If your enumerator wants to remove certain entries, but set aside pointers

  * to other entries that it retains, it can use PL_DHashTableRawRemove on the

  * entries to be removed, returning PL_DHASH_NEXT to skip them.  Likewise, if

  * you want to remove entries, but for some reason you do not want entryStore

  * to be shrunk or compressed, you can call PL_DHashTableRawRemove safely on

  * the entry being enumerated, rather than returning PL_DHASH_REMOVE.

  */

 typedef PLDHashOperator

 (* PLDHashEnumerator)(PLDHashTable *table, PLDHashEntryHdr *hdr, uint32_t number,

                       void *arg);

 NS_COM_GLUE uint32_t

 PL_DHashTableEnumerate(PLDHashTable *table, PLDHashEnumerator etor, void *arg);

 typedef size_t

 (* PLDHashSizeOfEntryExcludingThisFun)(PLDHashEntryHdr *hdr,

                                        mozilla::MallocSizeOf mallocSizeOf,

                                        void *arg);

 /**

  * Measure the size of the table's entry storage, and if

  * |sizeOfEntryExcludingThis| is non-nullptr, measure the size of things

  * pointed to by entries.  Doesn't measure |ops| because it's often shared

  * between tables, nor |data| because it's opaque.

  */

 NS_COM_GLUE size_t

 PL_DHashTableSizeOfExcludingThis(const PLDHashTable *table,

                                  PLDHashSizeOfEntryExcludingThisFun sizeOfEntryExcludingThis,

                                  mozilla::MallocSizeOf mallocSizeOf,

                                  void *arg = nullptr);

 /**

  * Like PL_DHashTableSizeOfExcludingThis, but includes sizeof(*this).

  */

 NS_COM_GLUE size_t

 PL_DHashTableSizeOfIncludingThis(const PLDHashTable *table,

                                  PLDHashSizeOfEntryExcludingThisFun sizeOfEntryExcludingThis,

                                  mozilla::MallocSizeOf mallocSizeOf,

                                  void *arg = nullptr);

 #ifdef DEBUG

 /**

  * Mark a table as immutable for the remainder of its lifetime.  This

  * changes the implementation from ASSERTing one set of invariants to

  * ASSERTing a different set.

  *

  * When a table is NOT marked as immutable, the table implementation

  * asserts that the table is not mutated from its own callbacks.  It

  * assumes the caller protects the table from being accessed on multiple

  * threads simultaneously.

  *

  * When the table is marked as immutable, the re-entry assertions will

  * no longer trigger erroneously due to multi-threaded access.  Instead,

  * mutations will cause assertions.

  */

 NS_COM_GLUE void

 PL_DHashMarkTableImmutable(PLDHashTable *table);

 #endif

 #ifdef PL_DHASHMETER

 #include <stdio.h>

 NS_COM_GLUE void

 PL_DHashTableDumpMeter(PLDHashTable *table, PLDHashEnumerator dump, FILE *fp);

 #endif

 #endif /* pldhash_h___ */